September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Gene therapy in the Opn1mw Knock-out mouse, a model for blue cone monochromacy, leads to long-term M-cone restoration
Author Affiliations & Notes
  • Ji-Jing Pang
    Ophthalmology, University of Florida, Gainesville, Florida, United States
  • Yuxin Zhang
    Ophthalmology, University of Florida, Gainesville, Florida, United States
    Ophthalmology, First Affiliated Hospital, Nanjing Medical University, Nanjing, China
  • Ping Zhu
    Ophthalmology, University of Florida, Gainesville, Florida, United States
  • Wen-Tao Deng
    Ophthalmology, University of Florida, Gainesville, Florida, United States
  • Jie Li
    Ophthalmology, University of Florida, Gainesville, Florida, United States
  • William W Hauswirth
    Ophthalmology, University of Florida, Gainesville, Florida, United States
  • Footnotes
    Commercial Relationships   Ji-Jing Pang, None; Yuxin Zhang, None; Ping Zhu, None; Wen-Tao Deng, None; Jie Li, None; William Hauswirth, AGTC (F), AGTC (P)
  • Footnotes
    Support  BCM Families Foundation, NIH grants EY023543 and EY021721, FFB, MVRF, and RPB, Inc.
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 1166. doi:
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    • Get Citation

      Ji-Jing Pang, Yuxin Zhang, Ping Zhu, Wen-Tao Deng, Jie Li, William W Hauswirth; Gene therapy in the Opn1mw Knock-out mouse, a model for blue cone monochromacy, leads to long-term M-cone restoration. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1166.

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      © 2017 Association for Research in Vision and Ophthalmology.

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Abstract

Purpose : Human cones containing L/M/S-opsin are sensitive to long/middle/short wavelength visible light. Mouse cones contain only M/S-opsin. Opn1mw knock-out mice lack M-opsin expression while maintaining a normal cone number and S-opsin expression without progressive cone degeneration. Blue Cone Monochromacy (BCM) patients only express S-opsin with reduced photopic acuity that is relatively stable. Therefore, the Opn1mw KO mouse is a good model to establish preclinical efficacy and safety data for a future BCM clinical trial, particularly when the gene therapy is performed in adult mice. We therefore tested whether AAV-mediated M-opsin expression in cones of Opn1mw KO mice at three months of age can restore M-cone function/structure for an extended time post treatment.

Methods : At postnatal day 90 (P90), one μl of AAV5-PR2.1-mouse-M-opsin vector (1013 vector genome particles/ml) was injected subretinally into one eye of each Opn1mw KO mouse. The other eye was uninjected and served as a control. M-cone mediated ERGs were recorded at seven months after injection. Treated and untreated eyes were harvested immediately after ERG recordings for immunohistochemical studies.

Results : Seven months after treatment, nearly normal rod mediated ERG waveforms were recorded in either treated or untreated Opn1mw KO eyes. Cone or S-cone mediated ERGs were also recordable from treated and untreated eyes; M-cone mediated ERGs were restored only in treated eyes, with about 40% of the normal b-wave amplitudes. There was no recordable M-cone ERG in untreated eyes. Cone-opsin immunostaining of retinal whole mounts showed that S-opsin was present in both treated and untreated retinas while no M-opsin was evident in untreated retinas. In contrast, abundant M-opsin positive cones were observed throughout the retina in treated eyes. Frozen retinal sections showed that AAV-mediated M-opsin expression not only co-localized with S-opsin expression in cone outer segments in the central and inferior retina, but was also found in the superior retina which had little or no S-opsin.

Conclusions : Since Opn1mw KO mice express only S-opsin, they serve as a good model for human BCM. AAV5-PR2.1-mouse-M-opsin mediated gene therapy initiated at P90 restores M-opsin expression and M-opsin function for at least seven months in Opn1mw KO mice. These results serve as a baseline for developing a BCM gene therapy clinical trial.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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